1. Field of the Invention
The invention is a medical device designed to facilitate insertion of a catheter into a patient's body.
2. Background of the Prior Art
Catheter insertion devices are well known in the art. When a catheter is inserted into a patient for the intravenous delivery of a fluid, a disposable needle passing through the catheter cannula is utilized to make a puncture to permit entry of the tip of the cannula into the patient. The needle is then withdrawn leaving the catheter in place either for a direct hook up to a bottle of fluid to be delivered, or to be capped for later use. The needle which is now contaminated with blood or other body fluid must be disposed of without creating a risk of needle sticks to medical personnel which are engaged in the operation of inserting a catheter. A danger to clean up and medical waste disposal personnel continues if the used needles are not rendered harmless in some way. Caps or covers that can be mounted over the needle are not a satisfactory solution because they must be put in place and can come loose and expose the used needle. An excellent discussion of the problems associated with various approaches and uses of cannula insertion products is found in Kulli, U.S. Pat. No. 4,747,831 which is incorporated herein by reference.
Retractable needles have been recognized as the best solution of these problems. A number of these approaches are disclosed in U.S. Pat. No. 4,747,831, mentioned above, which includes an external latch mechanism which is pushed to release a spring loaded needle which is withdrawn into the chamber of the device. Some embodiments have a sliding block and retractable fingers which depress spring loaded ears to allow retraction of the needle holder, racheting devices which unlatch the needle holder by rotation of parts and even frangible parts which are broken when a plunger is pushed forward. Dysarz, U.S. Pat. No. 5,129,884 is another example of an external latch which may be disengaged to allow a needle holder to withdraw a needle into the main body of the device. Walter, U.S. Pat. No. 4,828,548 discloses a holder having a piston which may be operated on by vacuum to withdraw a needle. Erskine, U.S. Pat. No. 5,501,675 is a more recent version of a latch operated device wherein a needle holding part may be released with an external latch.
The devices of the prior art often have too many complicated parts which are difficult to manufacture and especially difficult to assembly in a high speed manufacturing operation. Many of them are prone to premature firing during handling and with some it is difficult to know when the needle is safe. Disengagement of the catheter assembly from the retraction device is not fully under the timing and control of the medical operator because retraction results in immediate separation of the device form the cannula assembly. With the present invention, the assembled catheter introducer is handled as a unit. When the operator verifies that the needle is properly inserted, one hand can hold the connector that remains attached to the patient while the other hand separates the retraction body which upon separation is automatically retracted without the necessity of locating or pushing any buttons or movable parts. A portion of the hand rests against the cannula to prevent blood flow until the other hand inserts the conventional tube into the catheter connector to start the infusion of fluid. Immediately after separation the retraction body safely contains the retracted needle and the removed part is safely discarded.